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EQMOD Pulseguide settings


lukebl

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Hi,

During the current seemingly endless cloud, I'm tweaking a few things to sort out my imaging and guiding. I am guiding with PHD and EQASCOM just wondered if anyone adjusts the pulseguide settings, and what effect adjusting them has?

Mine is set at the default x0.10, which is the minimum setting. My guiding is far from perfect and I get trailing after around 6-8 minutes which I'm certain isn't caused by flexure or bad PA. Would increasing these settings change much?

Here's a screen grab. The pulseguide settings are top right.

post-16549-133877657526_thumb.jpg

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Yep, just fired it up and mine are both at x0.9 (max) by default - I know I haven't ever moved them as I'm just setting up for pulseguiding.

BTW, there is a new version of EQMOD (1.23p) and ASCOM v6 drivers are now out.

Thanks very much Roger. That's very interesting. Perhaps at last I've got to the root of my guiding issues. I'll adjust the settings and see what happens.

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Set them to 0.5 to start with and see how things go. You don't want them too high as small errors will require very short guide pulses and these are less likely to be accurately implemented. On the other hand you don't want them so low that they cannot keep up with the max rate of change present in your mounts periodic error.

Chris.

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And unless I misunderstand the way it works, calibrate at 100% then tweak the settings once guiding starts, correct?

Gary

If you are referring to the EQMOD "gain" sliders on the pulseguide monitor screen - then yes.

The gain sliders just provide a method to adjust the level of correction being applied whilst guiding is active. Depending on the autoguiding software you are using you may find that the autoguider itself provides similar/equivalent functionality.

Chris.

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Thanks gents. I had a quick try last night in between the clouds, with the Pulseguide setting increased from 0.1x to 0.5x. Still some trailing even after only 5 minutes. The trouble is, there seem to so many variables in the PHD/EQMOD settings, with little explanation of what effect changing them has, that it's hard to know which one might be the root cause (assuming flexure, backlash and PA aren't the issue). Next clear night I'll have to try a series of test runs, changing each setting after each one till I hit the spot.

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There are really not many settings in EQMOD you need to worry about. Just set the guide rate (the speed at which the mount will move during a guide pulse) and set the minimum pulse width down to the minimum of 20ms (20ms is about the limit to which any timings can be accurately implemented).

The graph in PHD should show you how well your guide star is being tracked (or you could log the guided data an pull it into pecprep)- if your star trails work out longer then the deviations shown then you most likely have a flexure problem.

Chris.

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